How to test if a Blower Motor is functioning properly using a multimeter?

1. Measure the motor winding resistance

Set the multimeter to the Ω (ohms) range and measure the resistance of each of the three phase windings (U, V, W).

Under normal circumstances, the resistances of each phase should be similar and within the manufacturer's reference range (e.g., 2.6Ω, 0.7Ω, 0Ω corresponding to different speed ranges).

2. Check the insulation resistance

Use the insulation resistance range of the multimeter (or a megohmmeter) to measure the insulation resistance of each phase to the Blower Motor casing.

The insulation resistance should be greater than 1MΩ; a value lower than this may indicate insulation aging or moisture absorption.

3. Check the motor starting capacitor (if any)

Set the multimeter to the capacitance measurement range and measure whether the starting capacitor's capacitance value matches the nominal value (e.g., 10µF).

A failed capacitor will cause difficulty starting the motor or increased noise.

4. Verify the power supply voltage

While the Blower Motor is running, use a multimeter to measure the phase-to-phase voltage and phase-to-ground voltage to ensure they meet the rated voltage (e.g., 220V/380V).